Collapsible tap



R. A. BOEHIW. COLLAPSIBITE TAP. APPLICATION man. JUNE 9. 1919.

Patented July fi 192W.

3 SHEETS-SHEET l.

R. A. BOEHM.

COLLAPSIBLE- TAP.

APPLICATION FILED JUNE 9, 1919.

Patented July 6 mm 3 SHEETS-SHEET 3.

Kill

A C(lRlOltt/lllltlhl OF PENNSYLVANIA.

CULLAPSIBLJE TAP Application filed June '9,

to the accompanying drawings, and to the letters of reference marked thereon, formiug part oi: this specification.

My invention relates toimprovements in taps; particularly to that class thereol known as collapsible taps; the object of the invention being to provide a tap which is adj stable to thread work of varying diameters in which the cutters or chasers will be automatically released from contact with threads ofthe work after the tap has cut its required length, so that the tap can he removed from the worlr without the necessity of reversing or backing out of the threaded piece.

it :lurther object of my invention is the provision oi? a tap oi the character specified, which may be used for tapping to a depth greaterthan to the length oil the chassis.

it further object of my invention is to provide a tap ot' the character specified, which may be used for right or left hand threading by changing the chascrs only.

The LliGiLlllll'eS of my invention are hereinafter Fully described, explained, pointed out, and are illustrated in the accompanying drawin in which l igurc 1. is a side elevation oi my improved collapsible tap.

Fig. 2, is a vertical central section on the line 52 -2 in Fig. 1, showing portions of the mechanism in elevation.

Fig. 3, is a plan view of the lower end thereof.

Fig. 4-, is a central section of the body member thereof on the line 2-5 in Fig. 1..

Fig. 5, is a transverse section on the line 5---: in Fig. 2.

Fig. (3 is an elevation of the lower end oli the body member.

Fig. 7, is an elevation oi the chaser operating member.

Fig. 8, is a view of the lower end thereof.

Specification of Letters Patent.

Patented July 6, 192d.

1919. flerial No. 302,786.

Fig. 9, is a side elevation of the operating cam.

Fig. 10, is a side elevation of the cam sleeve.

Fig. 11, is a longitudinal central section of the part of the operating mechanism shown in Fig. 7.

Fig. 12, is a side elevation of the micrometer adjusting ring. 7

l ig. 13, is a view of the upper edge of one of the chasers.

Fig. id, is a side elevation of the shank hub with portions thereol broken away.

I am aware there are many collapsible rips shown and described in prior Letters Patent, but in all of those terms with which I am ii'amiliar there are many disadvantages which .it is the object of the present invention to ovi-arcome.

In many of the other forms of taps the depth that can be tapped is limited by the length of the chaser plate for the reason that the operating mechanism of the tap is of greater diameter than that of the chasers.

lln my improved tap ll indicates the body member thereof, in. the lower end 0t which are milled radial slots it (see Fig. 6) which ll preferably face with extra hard plates (6 and a which are secured within the slots A oi the body member A by means of screws a so that the faces of the radial slots A will not become worn or abraded from use. This body it is cylindrical in contour, otuniform diameter throughout its entire length, and is provided with a cylindrical chamber A which extends partially there through, and is provided at the intermediate portion thereof with internal threads At the inner end of the chamber A is a central opening [i of reduced diameter; the wall. oi? said opening being provided with longitudinal grooves a, which grooves coincide with the central lines of the radial slots it, it indicates a slot in the wall of the member A for the ope1.ting lever hereinafter described. A indicates a sight opening in the wall of the body member [ill for the purpose hereinafter described. a indicates a screw hole in the wall of the body member it for the purpose hereinafter described. (0'' indicates short longitudinal semi-cylindrical grooves in the interior sun face of the body member A at the upper end thereof. a indicates screw holes in the lower end of the body member A.

Within the body member A I place a member B (see Figs. 7 and 8) having on the lower end thereof inclined radial ribs B which are under cut on each side thereof; which ribs B enter the slots 0 in the inner end of the chasers C (see Fig. 13) ;the ribs B passing downwardly through the grooves a (see Figs. at and 6) in the reduced opening A, so that when the chasers C are placed within the slots A. in the lower end oi the body A, the dove-tail like slots C in the inner ends of said chasers will embrace the ribs ii on the lower end of the member ll so that a longitudinal movement of the member 13 will cause a radial movement of the chasers C.

The member B is provided with cams 13 which cams form a hub on the member B which into the reduced opening A of the body member A. The member B is provided with a longitudinal opening B in which I place a spring 3*, which operates to maintain the member B in constant contact with the adjusting ring Gr. Secured upon the lower end of tl o body member A by means 0; screws H is a dish H which retains the chasers 0 within the slots A. The disk ll is provided with the axle post H which enters the longitudinal opening B in tl e member B, and compresses the spring l5 therein. The disk H fits into a recess H (see Fig. 4) in the lower end of the body member A.

Upon the member B I place a circular operating member D which is of substantially the same diameter as the interior diameter of the body member A. and is provided with a circumferential groove D (see Fig. 9) adapted to receive a coiled spring H (see Fig. 2) for the purpose hereinafter set forth. At the lower side of the operating member D are cams (Z adapted to cooperate with the cams B on the member 13 to force the member l downwardly when the operating member D is turned toward the left. 011 the upper side of the operating member D are similar cams d oppositely inclined.

Upon the member B above the operating member 1) (see Fig. 2) I non-rotatably secure a cam sleeve F (see Fig. 10) having ams F on the lower end thereof: adapted to coi'iperate with cams a on the member l),

as shown in Fig. 2; the cam sleeve F being secured on the member B by means of a transverse pin F which passes through a transverse opening Z) in the upper end of the member B {see Fig. 11), so that when the operating member D is rotated toward. the

right the cl thereon will cooperate with the cams F on the sleeve F to raise the member B upwardly and thus cause an in wardly radial movement of the chasers U in the slots A. The lower side of the operating member rests upon the surface A at the upper end of the reduced opening A" (see Fig. 2), and within the body member A. l place an. adjusting ring (i (see Fig. l2) which is provided with screw lhrcads (l which engage the screw threads A in the body member 1 1 the lower ed e of said ring surface of the \Ti contacting with the upper operating member l). thereby preventing the operating member D from moving longitip dinally within the body member 'lhc adjusting ring (i is also provided with a knurled surface (i :Hlflpiltul to be engaged by the screw G (see Fig. 2) in the wall ol the body member A, wlmrcby said adjusting ring (i may be secured against ruluion within the body member A. Said adjusting ring (l is also provided with a graduated scale G and with small holes G which are visible and accessible through the opening A in the wall of: the body member A.

Secured to the operating member l) within the groove l) by means of a screw l) is the coiled spring E; said spring I) passing around back of the operating member l) and being secured to the screw l l (see Fig. 2) in the wall of the body member A; said spring E being adapted to cause the opcrating member D to revolve toward the right. J indicates the operating lever which passes through the slot A" and is sc .:urcd in the opening (Z (see Fig. 9) in the periphery of the operating member I), by means oi which lever J the operating member l) can be turned to the left to force the member ll downwardly.

In the upper end of the body A I place the hub K of the shank K. This hub K is provided in its periphery with semi-cylindrical grooves is (see Figs. 5 and ii) which coincide with the grooves of in the inner wall of the body member A. The grooves A: in the hub K do not extend entirely across the width of the hub K, but stop short of the lower edge thereof thus leaving a ledge 2: at the lower end of the grooves upon which the springs L rest. In others of the groovcs- 7ca I place short rods ill (see Figs. 2 and which rods M prevent the hub K from rotating within the body member A.

Upon the upper end of the body member A I secure a ring N by means ot screws which maintain the springs L and key-rods Ivl in place and prevents the witlulrawal oi the hub K from the body member The inner end of the hub K is reduced in diameter, as at K to permit it to enter into the adjusting ring G as shown in Fig. 2, and is provided with a central longitudinal opcning K adapted to receive the cam slccvc F. In the low r edge of the portion K of the hub K there is a recess 0 in which l place a locking bolt P (see Fig. 2) which is sccurcd therein by means of a bushing 1; said bolt P being normally held in extended position fl it as shown in Fig. 2 by means of a spring P in which position it extends into a hole in the operating member 1) shown in dotted lines in Fig. 2, when the lever d isturned to the position thereof shown in Fig. 2, to expand the chasers G said bolt P being withd "awn from said hole in the member l) when the body member is moved longitudinally downward on the hub ii thereby releasing the member D and permitting it to be rotated in the body member A by the spring l) that the operating lever J will swing to the right, as shown in Fig. 1, and withdraw thechasers G from the work, thus permitting the tap to withdraw from the work without the necessity of reversing the tap.

in ope *ation the shank K of the tap is placed in the tool stock of the lathe, and the piece of work is revolved. The lever d of the tap is manually swung to the position thereof shown in Fig. 2, so that the bolt P will lock the memberl) as shown in said figure, thus expanding the chasers (3 through the forcingof the member l3 downward by the cooperation of the camel? and (Z and the inclined ribs 13.

VVhen the tap has reached the limit of its cut thetool stockand chaser are moved backward thus causing the body A to move longitudinally on the hub h: and compress the springs L, and withdrawing the looking bolt P from its engagement with the member D, which, as above stated permits the spring E to rotate the member D to the right; and because of the cooperation of the cams d and ll, which causes an upward.

movement of the member B, thus causing the chasers C to withdraw from the work. To adjust the cutting diameter of the chasers C the ring Gr is turned to the right or left, as may be desired, thus permitting the members B and D to be raised or lowered, the scale shown on said ring in Fig. 12 being in substantially thousandths of an inch.

Having thus fully shown and described the construction of the mechanism embodying my invention, and the operation thereof, l. do not desire to be limited to the exact form and arrangement thereof, as many modifications thereof. will suggest themselves to those skilled'in the art without departing from the scope of my invention; therefore, what I claim as new and desire to secure by Letters Patent is 1. A collapsible tap comprising a body mei'nbcr having radial slots in one end thereof and a cylindrical chamber in the opposite end thereof, chasers slidably secured in said slots, longitudinally movable means within said body member engaging the inner ends of said chaser-s adapted to shift the same, the diameter of said chaser-s being greater than the diameter of said. body member, rotating means mounted on said longitudinz-illy movable means adapted to impart longitudinal. movement thereto, a shank, a hub thereon slidably mounted within the cylindrical chamber in said body member, means to prevent rotary movement of said hub within said body member, and means to yieldingly press said hub inwardly in said body member, substantially as set forth.

2. A collapsible tap comprising a body member of uniform diameter throughout its length, and having radial slots in one end thereof, chasers slid-ably mounted in said slots the diameter of which is greater than the diameter of said body member, mechanism within said body member to shift said Chasers from expanded to collapsed posi tion, a shank, a hub thereon slidably mounted within said body member, means to pre vent said hub from rotating within said body member, means to yieldingly press said hub inwardly with relation to said body member, means carried by said hub to lock the chaser shifting mechanism when the chasers are expanded when said hub is in its inward position, and to release it when the body member is moved longitudinally on said hub, substantially as set forth.

3. Acollapsible tap comprising a. body member of uniform diameter throughout its length, having radial slots in one end thereof, chascrs slidably secured in said slots, longitudinally movable means within said body member to expand and collapse said chasers, a rotating operating member mounted on said longitudinally movable means adapted to give longitudinal movement to the latter, means to yieldingly maintain said operating member in position to collapse said chasers,'a non-rotatable longitudinally slid-able shank secured in said body member, means operated by said shank to lock the chaser expanding mechanism in expanded position and to unlock the same by means of relative longitudinal movement between the shank and body member, substantially as set forth.

A collapsible tap comprising a body member, one or more chaser-s radially mounted in one end of said body member, a longitudinally movable member in said body having one or more axially inclined beads engaging the inner end of said chaser adapted to transform the longitudinal movement of said member into the radial movement of said. chaser, cams on said longitudinally n'iovable member, a rotary operating member mounted on said longitudinally movable member, cams thereon adapted to cooperate with the cams on said longitudinally movable member to raise the same upward or force the same downward, a spring to rotate said ope "ating member in one direction, a lever to rotate the same in the opposite direction, means within said body member to secure said operating memllltl ber against longitudinal movement with re lation to said body member, a spring pressed shank hub slidably and non-rotatably secured in said body member, a spring-pressed locking bolt carried by said shank hub adapted to engage said rotary operating member when it is operated by said lever, and to release the same when the body mem her is moved longitudinally on said shank hub, substantially as set forth.

5. A collapsible tap comprising a body member having radial slots in one end thereof and a longitudinal central opening therein communicating with said slots, a longitudinally movable member within said central opening, axially inclined beads therein extending radially into said radial slots, said member having a central longitudinal opening therein, a spring in said opening, chasers in said radial slots and engaging aid inclined beads, a disk secured on said body member adapted to retain said Chasers in said slots and incidentally to compress said spring, camson said longitudinally movable member, an operating disk rotatably mounted on said longitudinally movable member, cams thereon to cooperate with the cams on said longitudinally movable member to raise and lower the same, an adjusting ring engaging threads within said body member adapted to resist the upward thrust of said operating disk due to the action of said spring, a non-rotatable and longitudinally movable spring-pressed shank hub within said body member, means to secure said hub within said body member, a spring-pressed locking bolt carried by said hub, a lever to rotate said disk until th same is engaged by said spring-pressed locking-bolt, and a spring to rotate said disk in the opposite direction to collapse said chasers when the locking bolt is disengaged from 'said disk by causing the outward movement of said hub body within said body member, substantially as set forth.

6. A collapsible tap comprising a body member, one or more chasers carried thereby, mechanism centrally mounted within said body member adapted to engage and shift the radial position of the Chasers, means to adjust the longitudinal position of said mechanism within said body member spring mechanism to operate said mechanism to collapse said chasers, a shank sli.d ably'and non-rotatably secured within said body member, means carried by said shank to engage said centrally mounted mechanism and lock the same when the chasers are radially expanded, and release the same when the body member is moved longitudinally on said shank, substantially as set "forth.

7. A collapsible tap comprising a body member, one or more radially shiftable chassis carried thereby, a shank slidably and non-rotatably secured in the opposite end of said body member, a spring-pressed locking bolt secured in said shank parallel to the axis thereof, a longitudinally movable member centrally mounted within said body member, axially inclined beads on the lower end thereof adapted to engage chascis carried by said body member, whereby the longitudinal movement of said member is converted into the radial movement of: said chasers, cams on said longitudinally movable member, a rotating disk mounted thereon, cams on. said disk adapted to cooperate with the cams on said member to force the same upward or .lo\\'nward, an adjusting ring engaging screw threads within said body member to limit the upward movement of said disk, a spring to normally press said mechanism upwardly against said adjusting ring, a lever to turn said disk in one direction to be engaged by said locking bolt, and a spring to turn said disk in the opposite direction when released .l'rom said locking bolt, substantially as described.

8. it collapsible tap comprising a shank and a body member non-rotatably and slidably mounted thereon, springs to force said shank upwardly with relation to said body member, means to limit the axial movement of said members with relation to each other, radially slidable chasers mounted in the opposite end of said body member, a lever and spring operated rotary member longitudinally positioned within said body member, and a longitudinally adjustable ring secured within said body member above said rotary member, and mechanism. centrally mounted in said body member and said rotary member adapted to convert the rotary movement into longitudinal movement, and then into radial movement of said chasers, means on said shank to maintain the rotary member in its leveroperated position, and to release it to the action of its operating spring when said body member is moved longitudinally on said shank, substantially as set forth.

9. A collapsible tap comprising a body member having a concentric chamber therein, and radial slots in the end thereof communicating with said chamber through a central opening of reduced diameter, shiftable chasers in said slots, mechanism mounted in said central opening adapted to engage and shift said chascrs, rotatable means within said body member adapted to operate said mechanism, a spring to rotate the same in one direction, a lever projecting through a slot in the wall of said body member to manually rotate said means in the opposite direction, an adjusting ring engaging said internal screw threads in said body member to limit the upward move- Cir near-agree ment of said rotatable means, a shank nonrotatably and slidably secured in said body member having a portion thereof projecting into said adjusting; ring, and having a recess in the end thereof parallel with the axis thereof, a spring pressed bolt in said recess adapted to lock said rotatable means at the limit of the'manual operation there of, and to release the same when said shanl: and body members have relative longitudinal movement, substantially as set forth.

10. In a collapsible tap, a body member having radially shiftable chasers mounted therein, longitudinally movable chasershifting mechanism, rotatable mechanism within said body member adapted to control said. ehasershifting mechanism, a longitudinally movable shank non-rotatably secured Within said body member, means to yieldingly maintain the shank in its innermost position Within said body member, a spring); pressed bolt carried by said shank adapted to engage said rotatable mechanism and maintain it in position to expand said chasers during the thread cutting op eration, and to release the same When the tap is moved backward from the Work, substantially as set forth.

In. testimony whereof I aliix my signature.

RUDOLPH A. BOEHM. 

